Maester Aemon

Maester Aemon, whose real name is Aemon Targaryen II, is a Maester who has served the Night's Watch for many years.

His father had four sons, and thought it might be dangerous to have so many heirs, so he sent Aemon to the Citadel, where he forged his chain and became a Maester.

He served at the keep of his elder brother until his death. His whereabouts after that are unknown, until his father Maekar Targaryen died and he was summoned to court, where he was quietly offered the crown, which he refused, and his younger brother Aegon became the King. For fear that he could be used in a plot to usurp his brother, he went to The Wall to join the Night's Watch.

Maester Aemon told Jon Snow that the vows of every man of the Night's Watch has been tested at least once. He says he himself was tested three times, but the worst was when his entire family, excluding Daenerys and Viserys, were slaughtered under Robert's Rebellion.